test: mark test flaky on freebsd

Test name test-worker-message-port-message-before-close is too long for
a commit message description.

Refs: #31280

PR-URL: #32849
Refs: #28803
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

Author: sam-github

test/parallel/parallel.status

@@ -50,6 +50,8 @@ test-fs-stat-bigint: PASS,FLAKY
 test-http2-reset-flood: PASS,FLAKY
 # https://github.com/nodejs/node/issues/28803
 test-stdout-close-catch: PASS,FLAKY
+# https://github.com/nodejs/node/issues/31280
+test-worker-message-port-message-before-close: PASS,FLAKY
 
 [$system==aix]